Static electricity instrument having audible indicator



April 8, 1952 R C. WEBSTER 2,591,898

STATIC ELECTRICITY INSTRUMENT HAVING AUDIBLE INDICATOR Filed Aug. 25, 1948 YI-112.1.' /az fda.

YU i

Raymond@ Webster, Kansas City, fit/flo.;` A'assigner' to W. Anderson-,11nd, of 'corporationbf Missouri Appunti@ Angustia, 194s; serial No.V 45h38 t and more particularly toy anelectric "device capable, when placed in use. of positively detecting and-indicating( to the user thereofA the ,prsence of statical electricity .in virtually any body; `*This isn continuation in .part o'f Ico-pending" 'appli'- ation .serial :'Ns. ""1.."212n1ed"rvbuary 9. icas,

` now Patent No. 2,556,458, covering @Static ETec'- tnicity Indicator. y u j- :Itisia fundamentalprinciple of electiotythat,

whenjtwo vbodies coinei'nt'o rliotionalc'ontat' with eachfothen, static electricityis created in feachfol lsaidvlbodies andthi's phenomena is gnerally"cov` eredibythe/field of electro-Statics; Tlepres'ence of such static electricity.' whether "it consists 'of negative or positive charges, is oftentimes disadvantageousp, :and it is in many cases dangerous. 'llfhedanger VfactorV is .more predominant inthe eldfof In'cyliciriet` particularly in 'zones of anesf itis thegpnmery object yofniis vinventier;te profe thesia Whereexplos'ions' arecoin 'on because "of '2,0'

.l [U J Y Another object of this invention sito provide anfinstrurnent l'capablecf operation as above set forthwithou-t tnefulse-of aseparate DL 'Cjpo'w'er S1"1i 'ply.f` y i i f f A further object-foffthis invent-in isi-wrt vide A an instrument "havingf ai'Jxl-iblef'indVi'cating means' calpabief'ol util-zingf the fficlcycl'epow'er available in the unit for producing the 'indicating sound.`j"", w` Another irnpoitantobject vof this invention-is to "provdea `'ievite of :the aforementioned char acter operable upon-the Wellknownipninciple that positive or negative charges will induce voltage in'a conductor when eitheroffsuchchangesLorithe conductor moving andvv'hen theflatter is 1in th'e "eld ofsuclrrcharges,` andhav-in'g -zfneans -forf'lvisually and Y`audibly indicating-the positive or -ne'ga'- tive charges when thebody containing thesame 'comes N'into 'close proximity with itheinstrument. Other j'objectsof this invention v-will be made clear orbecome apparent "duringlthe-ccurse oftli'e fdllowinrsfpecication, reie'renoebing had to the accompanying drawing, wherein the single figure is 'asche'rnatic Wiring'diagrafm Ashow-"lng `a "static electricity `iinstruinent Ahav-ing 1an-audible indicator, "made in'accordancewith the vpresent inven- Ation.v t

vice anndicatcr forgstatic electiicity having b oth visual` ana' .audible indicating 'means 'es apart thereof and' 'provided 'with a. plurality 'of 4melectron tubes 'n'cluiiiier a .tube for receiving' negative jstatio chargesA and one for jr'eceiv'ingpositive static chargesl so arranged fand coupled relatively as to be extremen/.sensitive 'and ,uniformiy so 'forbnth negative' and 'positive static 'chargesgto beiindicated. Y

The 'most importantobject of this invention wherein the aforesaid nee'ativeyelectron "tubeis Aprovided VWith .a floating grid a'hd'the :positive indicating, tubehese gnu "so coupled within-the Electric` circuit as 'to1essenti'alLv;` also, be aii'oa'ting grid; t i j t A i@tiri-ther object of this 'irventienis to iarovie i e fh'igin'y negatively biased nesting ,en-d (in 'the i thewprovision of .aninstrumentasiabove stated'.

"Asabove indicated; the presence of Aelectrical 'charges taking "the form `of static electricity in various objects, including -the human-bodyjmay in Jmany :instances tev very detrimental to* -an 'attemptedresu'lt particularly in the field-ofme'di# eine.4 ,Itbecomes desirous; thereforeto "have nieansjfoi vquickly and easiiyjindi'atin'g thejprsh enceofsucnistatc charges; to `the endtliat steps t may be taken toeliminatejthe` same; Oft-entimes) suchelectrical charges innen-operating room* presiani-fin the body nf the surgeon himself, the instruments heimigh-t use; vthe `b'olyoi pa tient, and elsewhere;` cause-ifet'alieiplosions when fcrete-f-inv lthevv-presence-er niet-ny commi-stime v "Thegca's'e for hnnsingv1tuaily-` all of the :elec- 'trcal elerhent's'zof Vthe `instzumentabout to be described has not been illustrated :herein-and, obviously, lm ay .be made :many `different -ways asrneeds might dictatei l Suchpcaseshould be explosionproof, ,be sealed tightly against opening except by the factory, and A'have sufficient Wannings ,thereon as to tampering, attempted repair oral'terations. likewise, all connections, r plugs and reeeptanes should be explosion-proof, au to 'the endjlofs'aety during useinjoperating rooms and the like. Also, a'flaniearrestorshmild be As shown in the drawing, the instrument includes a plurality of electron tubes l0, I2, I4, I6, and I8; a transformer 22, having a primary winding 24 and a secondary winding 26; neon lamps 28 and 30; a milliameter 32; a speaker 34; an antenna or probe 36; lead lines 38 and 40; and a grounding wire 4,2. vj

It is contemplated that the lead lines 38 and 40 extend from within the case for the instrument and have a conventional plug for connection to an outlet that joined to a source of alternating current, electrical energy. The speaker 34 within the case will communicate with the exterior thereof, and neon lamp 30, as well as meter 32, will all be visible to the user of the device. Probe 38 must extend from the case and be insulated therefrom, and grounding wire 42 should be disposed for connection with any object in the operating room or elsewhere that is to be grounded for reasons of safety.

Transformer V22 supplies the power for the circuit of the instrument and serves to isolate the same from the source of energy with which lead lines -38 and 40 are connected. Thus, such'circuit can be safely grounded without, at the same time, grounding other.electrical circuits, also, having connection with said source of energy. A saturable reactor type transformer would perhaps be more satisfactory, but would be impractical because of the power needed, thereby increasing the size beyond the desired limits in instruments of this character. Y

Each of the lead lines 38 and 40, which join 4 tloned, by rubber and cotton braid wrappings or the like.

As will hereinafter appear, the speaker or earphone 34 serves as a signal alarm and should be of the high impedance type. In order to attain the necessary volume, it must, operate at a much higher voltage than normally intended. But, its use will be intermittent and its construction will be of such as to be capable of withstanding the abuse.

The two main power lines leading from the secondary 26 of transformer 22 are broadly designated by the numerals 62 and 64, respectively, it being noted that line 62 joins with previously numbered wire 48. For simplicity and to eliminate the need of a D. C. power supply, the cathodes of the Various tubes are connected alternately to the lines 62 and 64. In other words. cathodes 66 and 68 of these tubes I0 and I8, respectively, are connected to line 62,by wires 10 and 1,2, re spectively, and cathode 14 of tube |4 joins with line 62 by wire 16, meter 32 and Wire 18. f

A pair of interconnected cathodes 80 and 82 for vtube I2 connect with line 64 by wire 84, resistor 86, and a wire188, anda cathode 90 for .tube I6 has direct connection with line 64 by directly with the primary 24 of transformer 22,

has a fuze 44 interposed therein. The isolation transformer 22 is, therefore, fuzed in its primary 24 and any excessive current in either primary 24 or secondary 26 will cause one or'both fuzes 44 to melt. Thus, any failure in the instrument of this invention will not interrupt other electrical appliances or instruments of the voperating room or other establishment by melting of other safety fuzes in various electrical circuits having connection with the common source of energy.

The case for the instrument is indicated by the numeral 46 and connects, as does transformer 22 by wiring 48, with a wire 50 that is, in turn, grounded as at 52. Grounding wire or terminal 42, also, joins with wire 50 and serves to ground objects in the vicinity of the instrument through a resistance 54. This resistance 54 limits the rate of discharge to ground and helps tc minimize the discharge spark created when a charged element happens to come into contact with the grounded object to which terminal 42 is attached.

It isA contemplated that wire 5| constitute a third wire in the power cord receiving leads 38 and 40, the circuit demanding the grounding, not only` of the common `wire 48 from secondary 26, but of the case itself through wire 50. rlhe hospital gas machines, oper-ating tables, etc., can be grounded by means of 'terminal 42 through limiting resistance 54 that should be of about one (l) megohm.

The antenna terminal 36 is, also, isolated from the instrument circuit by a relatively high resistance 56, preferably of about 22 megohms, and by a pair of blocking condensers 58 and 60. These blocking condensers 58 and 60 are chosen to represent an infinite resistance to any direct current from the circuit and greater than 25 megohms to 60 cycle alternating current. Furthermore, terminal 36 is protected by a grounded metallic coupling and is well insulated, as above men- `Heating filaments 94, 96, 98, |00, |02 and |04 are provided for cathodes 66, 80, 82, 14, and 68, respectively, in the usual manner, which laments are interconnected, as can easily be traced in the drawing, and joined to secondary 26 of transformer as at |06, as well as to line 62 at |08. c

The tubes I0l and I4 constitute the negative and the positive detector tubes, respectively, of the circuit and operate essentially cn the floating grid principle. The tube |0 should have an infinite resistance between its control grid ||0 and its cathode'.66,whereas tube I4 should have atleast 1,000 megohms resistance between its control grid |2 and its cathode 14. It would be'desira'ble in this instrument for the control grid I I2 of tube I4 to, also, be of the same floating type, but 'such provision is impossible because it is necessary to have a sufficiently high negative voltage between grid I I2 and cathode 14 of tubev I4 to prevent current flow through tube I4. The Way in which such high negative voltage isattained will hereinafter be made clear. vGrid |'I2 of .tube I4 will, in eiect, be a oating grid, along with grid ||0 'of tube l0, because of the above-mentioned extremely high resistance between grid I I2 and cathode 14.

The control grids IIO and ||2 of tubes I0 and I4, respectively, are connected through condensers 58 and 60 by wires'||4, ||6, ||8, |20, and |22; aii to terminal 36, through resistor 56, by wire I Assuming lines 38 and 40 to be connected to a source of lelectrical energyand the instrument properly grounded,'it is apparent that as soon as filament 94 becomes heated, tube I0 will pass maximum current and a D. C. voltage will result across resistors |26 and |28, because of the presence of a condenser |30. It is to be noted that plate |32 lof tube |0 has connection with line 64 and that resistors` |26 and |28 are interposed in such connection, with condenser |30 shunted thereacross.

Resistors |28 and |28 are connected directly at point |34 with grid |36 of tube I2, by line |38. A negative voltage induced into control grid ||0 of tube l0 causes a decrease in the current flow scorgere through-rsistors-l sono 'Izjs 'futuro coun-agree fejspe'otjto oathodo so of tubo l2. i i i I.

l\"orrnkally,i4 the voltage Vacross resistor |28 is negative `'andr just suicient' to cause no flow of connecting point |34 Ito be more positive with currenthfrromcathode 80 to plate 1460i tube yI2.`

Plate '|40 i's'joined directly to line-62 by wireo|42 Whileiplate |44 joins with line 62 through avari-A ablefesistance |46,` across which is shunted a con ensei |48.

`Becnis'e of current- Vnow through resistor 86,

grid I`50fof tube VI2 `(which is joined to line 64 by wire'88f. Thiscu-rrent vconnez'ztion is the saine las tha'tb'f grid |350 controlling' the current toplate As grid I 540 becomesmore n'egativeior cathode 8 2 becomes'more positive) ,less current"willilow` through resistance |46 andthe negative voltage ongr'idol I0 of tube I4 becomes less.

yVoltage is applied: to grid ||2 of thepositive Y detector vtube I4 by 'Way of variable resistance |46, tliru'gli the neon lamp 23 fand a `l.resistor |54 4"(joinin'g directly with wire |22). Lamp 28 acts `as a very high resistance. (At least 1,000 megohms.) Enough negative voltage is applied vto the grid H2 of tube I4 so thatlitis nearly cfutfo.v About ``35 'volts will be ne'cessary'unless thejpositive side f the Voltage is not grounded, thereby requiring a much higher voltage for cut oli. Grid I 2 will remain very sensitive, however, e'ven though such high negative voltage is needed, sinceat about 30 volts, tube I4 "will still pass full current. Full current to cut off occurs between "-30 and t: 35 volts, with nearly all of the entirev change coming with a 1-Vol`t` change 'in the grid voltage. i "Since "the resistance values of neon lamps vary, it Iwill be necessary to select lamp 28. The high# er Agrid voltage necessary to cut off, the higher resistance of lamp 29 and the'more sensitive tube 14e/,111 bo. 1

` iglrresistances other than lamp 28 might be chosen but 'would add greatly to *the expense rfor the instrument. Also, the use of a larnp in this manner is Ai'idvanta'g'e'ous :because its resistance r I'ins constant and is'not subject to damage efr 'change 'because of Ioutside `elements such las dirtand moisture. y i l "Summa'rizing at this point, a negative charge induced at'the probe 36 makesgrid |10 of tube .I Il more negative, diminishing' the normal -ow oi current therethrough, 'since the normal *flow of current fromtube I6 causes avoltage'drop-across resistors les and 12e. mothervr/oros; the Ycrop voltage `across resistors |26 and |28 will be less Ih "a negative voltage at probe `-36 than during normal `opration ofthe instrument. i

as 'above "stated, there is normouy o negative voltage 'across resistor |46 and, therefore, 'be'- 'tween-'grid |I'2 and cathode 'Moftube vI4 that is sufficient to stop entirely any "current flow `in ISUN- :When Aa positive charge is inducedat :probe t36, tube I4, which normally passes no current yas above stated, is caused to pas's current by render'- 'ing thevoltage 'between cathode "I4 vBand grid 'I`'I2 ecessry "to, also, mak-'e isuch voltage rless negati-ve c 6 when 'a-'ngativecharge ispresent at probe 36by' use oftubesland I2. l This could be accomplished byconnectingcathode 66 and plate|32 of vtube l0 to lines 64 'and' 62, respectively, with resistors |26 and |28 and condenser |30 remaining in the plate circuit. With such reversal, wire |38 would VstillA connect lllngint |34 and join `directlywithgrid ||2 oftube to attain suon uniform sensitivity, the l'oathocos 66 and 14 of tubes I0 and I4, respectively, are

commonly joined to the grounded vline 62. With such common joinder, `a direct coupling between age between cathode 14 and grid ||2 of tube It less negative, when a negative charge is induced at probe 36.

By insertion of tubes I2, tube|4 `is controlled whena negative charge is induced at probe3`6, in the followingfmanner:

A negative charge at probe 36 causesgrid H0A of tube I0 to become more negative withres'pect to `its cathode 66 and `pointj|34 becomes morey positive with respect to line 61|.

Normally, there 'is no current -flow 'between cathode '80 andplate |,40`of tube I2 because grid |34 becomes :more positive, grid I36.'becomes less negative, permitting currentV flow between cathjode and'plate |40.

Normally, there is a current fdow` in tubeV I2 between cathode 82 and plate |44 and, when 'the current flow through resistor 86 increases, the flow of current from cathode 82 to plate |44 decreases. A decrease in voltage across resistor |46 is then present, causing a decrease in voltage between cathode "T4 and grid I2 of tube I4.Vv This makes grid I2 less negative. When a positive voltage is induced at' probe 36, such 'voltage will have no effect on thef grid |I0 oftube I0 as it is difcult to make the same more positive. Tube I4, however,'will bemade more negative and 'will begin t'o draw current.

This currentwill pass through resistor |55, caus' ing a voltage.` drop 'thereacross in thesame manner as was caused by the negative voltage on grid IIO of tube I0, initially impressed o niprobe 36. Thus, when the amount of voltage ,drop in 'ref sister `|46 beco'r'nes less, ,because cf presencepof negative charges 'at probe' satire negative voit-Y a'go impressed between' grid `H2 and cathode 'M of tube I 4 is proportionately reduced. Such reduc'- tion 'in `negative 'voltage lcauses current flow through tube I4 .proportional tothe amount Vvof negative voltage impressed. 1

The meter 3.2 .in the cathode circuit'of tube I4 serves two purposes, i. e., itshowsV when tube is at .cut oit, and it indicates the vvoltage induced at .probe 316. Meter 32 Ynormally registers zero because tube I4 draws no current. But, a-n indication will b'e made whenever either negative or positive charges are'present at probe `136. o 'ICurrent flow "in tube 4 :causes a 'voltage drop across la resistor y| 56 that is interposed between line 64 and plate |58 of tube I4, and a condenser r|66 is connectedacross resistor |56. A voltage is thereby induced between ca'thode 90 and :grid |62 of tube I6 that isequal to the voltage"'drop acrossresistor 1756. *Grid |162 i's, therefore, 'made negative with respect to cathode 'SU v4:of 'tube IS.

Such arrangement, however, 'would not aiord uniform sensitivity in measuring 'both1 positivel and negative charges existing at probe 436. Thus,1

' Since there is normally no current flowing through tube I4, there is no voltage drop across resistor |56. The impressed voltage between grid |62 and cathode 90 of tube I6 is zero, and maximum current flows through tube I6 and resistors |51 and |59. A condenser I6I is shunted across resistors |51 and |59. l

Tube I6 serves not only as an amplier but supplies the negative bias voltage for the power of half ywave impulses delivered by tube I8.

It is seen that any moving electrical field or movement of probe 36 in a stationary eld will cause a voltage to be induced at probe 36. Condensers 58 and 66 will be charged negative, whenever a negative charge is approaching probe 36V or a positive charge is moving away fromprobe 36. When a negative voltage moves away or a positive charge approaches probe 36, condensers 58 and 66 will be charged positively.

When condensers 58 and 6G are charged negatively, grids I| and II 2, of tubes I0 and I4, respectively, will be charged negatively, and conversely a positive charge in condensers 58 and 6G will charge grids I I6 and I|2 positively.

The grid voltage of tube I0 is maintained at contact potential voltage, since grid |||l is floating, and weak positive voltages induced at probe 36 will have little effect on it. Furthermore, since tube I4 is maintained at near cut off voltage, the negative voltage induced into itsl grid I I2 has little effect on it. Thus, tubes I0 and I4 are sensitive only to their own respective voltages.

It is necessary that the leads to grids IIIl and II2 be kept separate from the power lines 38 and 40, from ground terminal 42, and from lines 62 and 64. Sensitivity could be increased still further by separating condensers 58 and 66 and providing an antenna wire to each, with both antennas having a high resistance of about 22 megohms interposed therein.

It is to be noted that in order for antenna wire 36 to become alive (sparking voltage), it would be necessary to have afailure (short) in either tube I0, I4 or I6 andat `the same time a failure of either condenser 53 or condenser 60, together with a failure in resistance 56 and in the insulation of antenna 36. Even under the severest conditions, failure of one of these elements will not cause failure in one of the others.

It is to be noted that the above-described circuit is operable without the necessity of a separate D. C. power supply for the plurality of electron tubes used. All grid control voltages are maintained as D. C. by use of the units having a' resistor, together with a condenser shunted thereacross. Such resistors are designated by the gether with their respective condensers |36, |48, |60 and I6I. for tubes |2, I4, I6 and I8, respectively.

Having thus described my invention, what I claim as new and desire to secure `by Letters Patent is:

1. An instrument for determining the existence o! an electrostatic eld comprising means for conducting electrical charges in said eld; a pair of electrical, signal generating elements coupled.

with said conducting means, one of said elements being sensitive to positive charges only, the other element being sensitive to negative charges only; and means for amplifying the signals generated by said elements into an audio-frequency current.

2. An indicatingv instrument for determining the presence of either a positive or a negative charge on a body comprising a pick-up antenna adapted to be movably positioned adjacent to the body for induction of a charge thereon, a rst three electrode tube having its control grid coupled with said antenna and being operative to pass current through its output circuit in response to a positive charge induced on the grid thereof, a second three electrode tube also having its control grid coupled with said antenna and being operative to pass current through its output circuit in Vresponse to a negative charge induced on the grid thereof, a pair of power supply conductors connected to said tubes, the Plate element of each tube being connected to only one of said conductors, biasing means associated with the grid circuits of said tubes and asignal indicator in the output circuit of said first named tube and being operably responsive to current iiow through said output circuit when either of said tubes operatively responds to positive or negative charges induced on a respective grid.

3. An instrument for determining the presence of an electrostatic eld and of the type having a w pick-up antenna adapted to be movably positioned in said eld, said instrument comprising a positive charge detector tube and a negative charge detector tube, each tube having anode, cathode and grid elements, a pair of power supply conductors, the cathodes of both tubes being connected to one conductor and the plates of both tubes being connected to the other conductor, the antenna being connected to both of the control grids of the tubes, said positive charge detector tube normally having its grid biased negatively to tube cut-oi condition, biasing means operably responsive to a reduced current flow in the negative charge detector tube for reducing the negative bias on the grid of the other tube to permit current to flow therethrough, an indicator operatively responsive to current flow through the anode-cathode circuit on said other tube, whereby a negative charge induced on said antenna and the grid of the negative charge detector tube will cause a reduced current therethrough, or a positive charge induced on the grid of the positive charge detector tube will reduce the negative bias thereon to permit an increase of circuit through its anode-cathode circuit.

4. An instrument for determining the presence of an electrostatic iield and of the type having a pick-up antenna adapted to be movably positioned in said field, said device comprising a first tube for detecting a positive charge and having an anode-cathode circuit and a control grid, said grid being connected to the antenna, a second tube having separate pairs of triode elements therein, each triode comprising anode, cathode and grid elements, the plate of one triode being connected through a iirst biasing resistance to the grid of said rst tube, said latter grid being connected also to the antenna, a third negative charge detector tube having anode, cathode and grid elements, a second resistance connected at one point to the plate of said third tube, the two grids of the second tube being connected to other points on said resistance whereby variation 'in current ow through the resistance is operative to bias the last named grids, an indicator operatively responsive to current flow in the anodel tor tube and the other triode and, whereby an induced negative charge on said*` antenna and said third tube grid will reduce current flow therethrough, and through said'sec'ondresistance and said other triode and its connected resistance, thereby to reduce the negative bias on said ilrst tube grid to permit current vflow in its anodecathode circuit to energize the indicator. ,l

5. A thermionic device for indicating both a positive or a negative charged condition of a body comprising a rst or positive charge detector tube, a second or negative charge detector tube and an intermediate bias control tube, the rst and second tubes having anode, cathode and grid elements, said intermediate tube having a rst and a second triode element unit therein, each unit comprising anode, cathode and grid elements, an A. C. transformer having output leads connected to the anode and cathode elements of each tube, the cathodes of the rst and Athe second tubes being connected to one lead and the cathodes of the intermediate tube being connected to the other lead, a first biasing resistance connected at one end point to the anode of said second tube. the two grids lof the intermediate tube being connected to other points on said resistance, an electrostatic field pick-up. antenna connected vto the grids of the first and second tubes, a second biasing resistance connected in circuit between the plate of one triode and the grid of the rst tube, said resistances being operative normally when no charge is being induced on the antenna to block current iiow through said first tube and through the anode-cathode circuit of the triode associated with the second resistance, but to permit current flow through said second tube and the other triode circuit, the current flow through both resistances and associated tubes being varied when either a positive or a negative is induced on the antenna in a man 10 A ner to reduce the negative bias on said iirst tube to permit current ow through its anode-cathode circuit, and an indicator operably responsive to current flow through said rst tube. 4 6. A thermionic device for indicating both a positive and a negative charged condition of a body comprising a iirst tube for detecting a positive charge and a second tube for. detecting a negative charge, each tube having anode, cathode and grid elements, power supply conductors for energizing said tubes, the cathodes of both tubes being connected to one conductor and the anodes of both tubes being connected to the other conductor, a pick-up antenna adapted to be positioned within the field adjacent to the body and being connected to the grid of each tube, an indicator operatively responsive to flow of current in the anode-cathode circuit of said rst tube, a biasing resistance connectedto the anode of said second tube and being coupled in circuit with the grid of the rst tube, means operably responsive to a decreased current flow in the anode- Vcathode circuit of the second tube and in said bias on the grid of the second tube and cause a decrease of current therethrough or to permit a positive charge thereon to also reduce the negative bias on the first tube and to increase the current iiow through its anode-cathode circuit to operate said indicator. Y

RAYMOND C. WEBSTER.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES VPATENTS 

